LETTER TO THE EDITOR
Papillary muscle hypothesis of idiopathic left ventricular tachycardia: reply
Akihiko Nogami, MDa
a Division of Cardiology, Yokohama Rosai General Hospital, 3211 Kozukue, Kohoku, Yokohama, Kanagawa 222-0036 Japan
akihiko-ind{at}umin.ac.jp
We are grateful for the opportunity to respond to the comments by Dr. Chen et al. concerning our recent article in the Journal (1). I was very impressed by the study of Joyner et al. (2), that reported on longitudinal dissociation of ventricular muscle and Purkinje signals in isolated papillary muscle of a dog. According to Figure 1B in their article, pacing from a Purkinje strand inserting into the apex of the papillary muscle resulted in apex to base Purkinje activation, which then excited the ventricular muscle via the Purkinje-muscle junction at the base of the papillary muscle with propagation of the excitation from the base to apex of the papillary muscle. Their Figure 1B is similar to our Figure 2A, as Dr. Chen et al. have suggested. According to the results of Joyner et al. (2), our diastolic potential (P1) appeared to be the result of a signal from the local ventricular muscle of the papillary muscle, and our presystolic potential (P2) that from the local Purkinje activation of the papillary muscle. However, there are several differences between our study and the study by Joyner et al. First, while the Purkinje-muscle junction in their study was located at the base of the papillary muscle, the Purkinje-muscle transmission occurred at the infero-apical septum in our study. The position of the octapolar electrode catheter shown in our Figure 1 differed from the site of the posterior papillary muscle. The activation sequences of the Purkinje potential during sinus rhythm may also differ. Because Purkinje fibers enter the anterior and posterior papillary muscles through the trabeculae carneae, the activation sequence of the Purkinje potential in the papillary muscle during sinus rhythm must be from the apex to the base. However, our P2 was recorded earlier from the proximal than the distal electrodes during sinus rhythm. We think that P1 is the potential from the trabeculae carneae. Trabeculae carneae form ridges, bridges and small papillary muscles. Lai et al. (3) proposed a false tendon or interlacing Purkinje fiber as a link between the slow conduction tissue and left posterior fascicle. Gallagher et al. (4) and Thakur et al. (5) have also implied that the left ventricular muscular band may be the anatomic substrate for idiopathic left ventricular tachycardia. However, Lin et al. (6) have shown that the left ventricular muscular band is not the specific arrhythmogenic substrate for this tachycardia. However, trabeculae carneae or small papillary muscles cannot be detected by echocardiography. Nevertheless, longitudinal dissociation of the ventricular muscle and Purkinje signals from the papillary muscle and trabeculae carneae, and the presence of the Purkinje-muscle junction, are important in considering the reentry circuit of verapamil-sensitive idiopathic left ventricular tachycardia.
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References
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1. Nogami A, Naito S, Tada H, et al. Demonstration of diastolic and presystolic Purkinje potential as critical potentials in a macroreentry circuit of verapamil-sensitive idiopathic left ventricular tachycardia. J Am Coll Cardiol. 2000;36:811–823[Abstract/Free Full Text]
2. Joyner RW, Ramza BM, Tan RC. Effects of stimulation frequency on Purkinje-ventricular conduction. Ann NY Acad Sci. 1990;591:38–50[Medline]
3. Lai LP, Lin JL, Hwang JJ, Huang SK. Entrance site of the slow conduction zone of verapamil-sensitive idiopathic left ventricular tachycardia: evidence supporting macroreentry in the Purkinje system. J Cardiovasc Electrophysiol. 1998;9:184–190[Medline]
4. Gallagher JJ, Selle JG, Svenson RH, et al. Surgical treatment of arrhythmias. Am J Cardiol. 1988;61:24A–44A[CrossRef]
5. Thakur RK, Klein GJ, Sivaram CA, et al. Anatomic substrate for idiopathic left ventricular tachycardia. Circulation. 1996;93:497–501[Abstract/Free Full Text]
6. Lin FC, Wen MS, Wang CC, Yeh SJ, Wu D. Left ventricular fibromuscular band is not a specific substrate for idiopathic left ventricular tachycardia. Circulation. 1996;93:525–528[Abstract/Free Full Text]
Related Article
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Papillary muscle hypothesis of idiopathic left ventricular tachycardia
- Peng-Sheng Chen, Hrayr S. Karagueuzian, and Young-Hoon Kim
J. Am. Coll. Cardiol. 2001 37: 1475-1476.
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